Frequency of healthcare utilisation by adults who use illicit drugs: a systematic review and meta-analysis

Background and aims – People who use illicit drugs have poor health outcomes and face barriers to medical care. However, there is limited population-based research into healthcare utilisation by this group.

Methods – We searched Medline, EMBASE and PsychINFO from 1 January 2000 to 4 December 2018 for observational studies reporting the rate or cumulative incidence of all-cause healthcare utilisation by adults who use illicit drugs. A protocol has been registered with PROSPERO (identifier CRD42017076525).

Results – Our search identified 5,528 studies, of which 92 were included; 84% from North America and Australia. Most studies focused on people using heroin, methamphetamine or crack cocaine, or who had a diagnosis of drug dependence. We were able to conduct meta-analysis of rates across 25 studies reporting ED episodes and 25 reporting hospitalisations, finding pooled rates of 151 (95% CI 114-201) and 41 (95% CI 30-57) per 100 person-years respectively; on average 4.4 and 7.1 times the general population. Heterogeneity was very high and was not explained by drugs used, country of study, recruitment setting or demographic characteristics. There was limited research into utilisation of primary care, but five studies found that people who use illicit drugs attend primary care more often than ED. Across settings, most episodes were related to infections, injuries and non-communicable diseases rather than drug-specific problems. Predictors of healthcare utilisation within studies were consistent and included unstable housing, injecting drugs and mental health problems. Opioid substitution therapy was associated with reduced ED presentation and hospitalisation. There was minimal research on healthcare utilisation by people using ecstasy/MDMA, powder cocaine, hallucinogens or novel psychoactive substances.

Conclusions – People who use illicit drugs visit ED or are hospitalised multiple time more often than the general population. Research is needed to identify interventions that can promote planned and preventative healthcare and reduce emergency care. The wide variation in frequency of healthcare utilisation across studies may reflect important sub-national differences in health service accessibility.